1. Field of the Invention
This invention relates to an eddy current flaw detecting endoscope apparatus whereby a flaw of a part of an object to be inspected is detected without invading the object and an observed image of the above mentioned object is obtained.
2. Related Art Statement
Recently there is extensively used an endoscope (scope or fiberscope) whereby organs within a body cavity can be diagnosed or inspected by inserting an elongate insertable part into the body cavity. For not only medical but also industrial uses, such an endoscope is used to observe and inspect an object within a tube of a boiler, turbine, engine, machine or chemical plant or within a machine.
For the above described industrial uses, an eddy current flaw detecting apparatus or endoscope apparatus is practically used to inspect and observe a flaw such as a scratch or corrosion within a pipe line.
With the above mentioned eddy current flaw detecting apparatus, an eddy current is induced into an inspected object (dielectric) by an alternating magnetic field of an eddy current detecting coil moved within object such as a pipe line and a phenomenon that the value of this eddy current varies with a scratch or corrosion existing within the inspected object is taken as an impedance variation of the above mentioned coil so that the size and position of such flaw as the above mentioned scratch or corrosion may be detected at a high speed without invading the object.
With the above mentioned endoscope apparatus, an insertable part provided at the tip with an observing window is inserted into an object to be inspected and an object image obtained from the observing window is optically observed. There are used also various kinds of endoscope apparatus for electrically observing an object image obtained from an observing window by using an imaging means such as a charge coupled device (CCD).
An apparatus in which an eddy current flaw detecting apparatus and endoscope apparatus are combined with each other is shown in the publications, for example, of Japanese Patent Applications Laid Open Nos. 38558/1986, 155754/1986 and 90758/1988 and Japanese Utility Model Applications Laid Open Nos. 157670/1981 and 33313/1985.
In the publication of the above mentioned Japanese Patent Application Laid Open No. 38558/1986, an eddy current flaw detecting coil is provided near a scope head of an endoscope (fiberscope). In the publication of the above mentioned Japanese Patent Application Laid Open No. 155754/1986, at least two of a a) head provided with a sighting camera, b) head provided with an eddy current flaw detecting probe and c) head provided with an ultrasonic flaw detecting probe, are connected to a connecting member at the tip so as to detect a flaw by rotating each head. In the publication of the above mentioned Japanese Patent Application Laid Open No. 90758/1988, an eddy current flaw detecting means and an image guide by which a pipe can be observed over the entire inner peripheral surface are provided in the insertable part at the tip. In the publication of the above mentioned Japanese Utility Model Application Laid Open No. 157670/1981, an eddy current flaw detecting coil is removably provided in a bore scope at the tip. In the publication of the above mentioned Japanese Utility Model Application Laid Open No. 33313/1985, an optical fiber tip part of an endoscope (fiberscope) is arranged in the head part inserted through a pipe and an optical system for directing the optical axis of the above mentioned optical fiber to the pipe wall and an eddy current flaw detecting inspecting coil are provided so that an object image may be transmitted by the optical fiber from the tip of the endoscope to the base side and may be optically observed. According to such apparatus, a flaw part within a pipe can be detected by an eddy current or ultrasonic wave and can be visibly observed.
However, in the arts shown in the publications of the above mentioned Japanese Patent Application Laid Open Nos. 38558/1986, 155754/1986 and 90758/1988 and Japanese Utility Model Application Laid Open No. 90785/1988, no control signal will be input and output between a video tape recorder recording an endoscope image and eddy current flaw detecting apparatus and therefore the picture recording by the video tape recorder (abbreviated as the VTR hereinafter) and the inspection by the eddy current flaw detecting apparatus has been made without any relation. Also, in case only a flaw part is to be recorded, whenever a flaw is detected by the eddy current flaw detecting apparatus, the VTR will have to be switched on/off by a switch or the like and the on/off operation is a problem.
In the art shown in the publication of the above mentioned Japanese Utility Model Application Laid Open No. 33313/1985, data such as the size of the flaw detected from the eddy current flaw detecting apparatus will be recorded in the VTR as superimposed on the endoscope image as video signals. However, in case the image of the flaw obtained from the endoscope apparatus and data such as the size of the flaw obtained from the eddy current flaw detecting apparatus are to be recorded in the VTR, the VTR will have to be always inputting the video signal from the eddy current flaw detecting apparatus and recording the endoscope image and therefore the endoscope image in which no flaw is produced, that is, which is not required to be inspected will be recorded and the video tape will be wasted.
The same as in the art in the publication of the above mentioned Japanese Patent Application Laid Open No. 38558/1986, in case only the flaw part is to be recorded, the VTR will have to be switched on/off by a switch or the like, the on/off operation will be a problem and the inspecting time will become long.
Also, in order to accurately obtain the depth or position of the flaw, for example, in case the insertable part is inserted or pulled, the insertable part will have to be kept stable within the object lest a movement should be produced in the flaw position of the flaw detection sensing member by the vibration of the insertable part.
In case only one eddy current flaw detecting coil or only one set not independent as shown in the publications of the above mentioned Japanese Utility Model Application Laid Open No. 33313/1985 and Japanese Patent Application Laid Open No. 90758/1988 is provided in the tip part of an endoscope, the inspecting time will become long.
In a flaw detecting endoscope apparatus using a solid state imaging device, an imaging signal from the solid state imaging device and an eddy current flaw detecting electric signal will interfere with each other, the image will be disturbed or a flaw or the like will be detected erroneously by a pseudo signal.